MLH1 Gene Expression and Pathologic Factors in Iranian Patients with Colorectal Cancer

MutL homolog (MLH1) is a key component of heterodimeric complex MutLα, which recognizes and repairs base-base mismatches or insertion/deletion loops that arise from nucleotide misincorporation. In the absence of MLH1 protein, the number of unrepaired mismatches will increase and cause tumors in organs. The present study aimed at quantitative analysis of MLH1 gene expression and its association with depth of tumor invasion (T) and lymph node invasion (N) factors in blood samples of Iranian patients with colorectal cancer (CRC).

Blood samples from 33 patients with CRC were collected. RNA (Ribonucleic acid) was extracted and cDNA (Deoxyribonucleic acid) was fabricated according to the kit protocol extracted. The primer was designed by the Exon-Exon Junction method, and Real-time Polymerase Chain Reaction (Real-Time PCR) test was performed three times for MLH1 and β-actin (Beta-actin) genes. Data were analyzed in  REST 2009 Software, and a T-test was used to evaluate the expression of MLH1 gene and its association with T and N factors.

The results of Real-Time PCR in 33 patients with the male to female ratio of 42.5% to 57.5% and a mean age of 55 years demonstrated a significant decrease in MLH1 gene expression in the late stages of the disease (P<0.05 *). Furthermore, the reduction of expression in this gene was associated with T (P <0.05*) and N factors (P<0.05 *).

As evidenced by the obtained results, a direct relationship was observed between decreased expression of MLH1 gene and late stages of colorectal cancer. Moreover, the association of this gene with T and N factors was investigated and confirmed in several Iranian patients with colorectal cancer.